History will not look kindly on Russia’s war with Ukraine, with US officials describing it as an unprovoked war of aggression directed by Vladimir Putin.

       “He’s perpetrating violence on a neighbouring nation that presented no threat to him. Innocent lives are being taken. We’ve seen casualties, we know there’s casualties on both sides of this conflict,” Pentagon press secretary John Kirby said during a press briefing on Monday.

       “This is a war of choice completely and totally avoidable. All the casualties are on his hands. All the blood is on Mr Putin’s hands,” he added.

       At least 64 civilians have been killed and more than twice that number have been injured during fighting in Ukraine, according to the United Nations. In the first day of Russian military operations alone, 130 military personnel were killed and more than 310 were injured, according to Ukrainian president Volodymyr Zelenskyy.

       Russian troops are still massing throughout the country with plans to take Kyiv as a top priority, but “stiff” Ukrainian resistance has meant Russia’s military is “a few days behind where they expected to be writ large in the country,” the US defence official said.

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       During Monday’s briefing, he also reiterated his hope that the Russian leader seeks a peaceful resolution to the crisis.

       “There’s nothing other than perhaps his own obstinance preventing Mr Putin from doing the right thing here and trying to find a way to stop this war, to deescalate the tensions, and to reengage in some sort of diplomatic peaceful path forward,” Mr Kirby said.

       Ukrainian and Russian officials held peace talks along the Ukraine-Belarus that concluded on Monday.

       Mykhailo Podolyak, a member of the Ukrainian delegation, reported that the Russian delegation “still has a very biased view of the destructive processes it has launched.”

       More talks may be held in the coming days.

       In the meantime, the US has firmly stated it has no plans to enforce a no-fly zone in Ukrainian airspace, a military engagement that many observers believe would heighten the risk of touching off a larger conflict between the US and Russia, potentially with nuclear implications.

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       Still, the White House says Americans shouldn’t fear a nuclear conflict on the horizon related to Ukraine, even as Russia has said it’s putting its nuclear forces “on alert” in response to what it called “aggressive statements” by NATO.

       “We are assessing President Putin’s directive and at this time we see no reason to change our own alert levels,” White House Press Secretary Jen Psaki told reporters on Monday.